1. Field of Invention
The present invention relates to a preventive or alleviating agent for medical symptoms by delayed allergy reactions, which contains an .omega.9-unsaturated fatty acid as an effective component, and to a food or drink with a preventive or alleviating effect on medical symptoms by delayed allergy reactions. Specifically, it relates to a preventive or alleviating agent, or a food or drink with a preventive or alleviating effect against medical symptoms by delayed allergy reactions which contains as an effective component at least one selected from the group consisting of 6,9-octadecadienoic acid, 8,11-eicosadienoic acid and 5,8,11-eicosatrienoic acid.
2. Related Art
Allergy reactions are classified into 4 types, types I to IV, based on the antibodies contributing to the reaction, differences in the reaction mechanisms, presence of complement, etc. Of these, type IV allergy reactions differ from the other types of allergy reactions in that antibodies thereto cannot be detected in the blood of individuals in such an allergic state, and it is elicited by lymphocytes. Because at least 12 hours must pass from invasion of the antigen into the allergic individual until appearance of the inflammatory reaction, the type IV allergy reaction is known as "delayed type hypersensitivity".
The T lymphocytes (sensitized T lymphocytes) of individuals in an allergic condition react with the antigen, triggering the T lymphocytes to release lymphokines (macrophage migration inhibitory factor (MIF), macrophage activating factor (MAF), mitogenic factor (MF), skin-reactive factor (SRF), chemotactic factor, neovascularization-accelerating factor, etc.), which function as inflammation mediators, and the biological activity of these lymphokines, together with the direct and indirect effects of locally appearing lymphocytes and other inflammatory cells, give rise to the type IV allergy reaction (delayed allergy reaction).
Delayed allergy reactions include tuberculin type reaction, homograft rejection reaction, cell-dependent type protective reaction, contact dermatitis hypersensitivity reaction, and the like, which are known to be most strongly suppressed by steroidal agents. Consequently, steroidal agents are effective against diseases which are caused by delayed allergy reactions; however, since long-term use of steroidal agents leads to the serious side-effect known as steroid dependence, there are difficulties associated with the termination periods and methods for their administration. It has been strongly desired, therefore, to develop non-steroidal delayed allergy reaction suppressants, which have few side effects.
On the other hand, it has been reported that synthesis of leucotriene B.sub.4 is inhibited in the cells of rats raised on feed containing the .omega.9-unsaturated fatty acid, 5,8,11-cis-eicosatrienoic acid (mead acid) (J. Exp. Med., The Rockefeller University Press, vol.178, Dec. 1993, p.2261-5), although it was not clear whether or not delayed allergy reaction was suppressed.